1. Field of the Invention
The present invention relates to the system configuration and method for controlling an image projection apparatus. More particularly, this invention relates to an image projection apparatus implemented with improved control processes for controlling a spatial light modulator and a light source of the projection apparatus.
2. Description of the Related Art
A projection apparatus implemented with a mirror device projects an image by reflecting the light emitted from a light source from the mirror device. Therefore, the number of the mirror elements of the mirror device determines the resolution of the projection apparatus. Since the mirror elements of the mirror device are formed on a semiconductor substrate, the resolution of the mirror device is therefore dependent on the size of substrate and the size of the mirror elements. While resolution may be improved by increasing the size of the substrate to increase the number of mirror elements formed on the substrate, a larger substrate however also enlarges the mirror device. This in turn introduces the problem of a projection apparatus becoming too large. It is therefore necessary to devise a method for improving the resolution of a projection image while maintaining the sizes of the projection apparatus and mirror device.
Accordingly, U.S. Pat. No. 7,052,142 discloses a method to improve the resolution while without increasing the number of the mirror elements of a mirror device. This method, known as wobbling technique is carried out by mechanically and minutely wobbles the mirror device to slightly change the directions of reflection, thereby making it possible to increase a pseudo number of mirror elements. The wobbling technique has the advantage of achieving the same effect in improving resolution as when the number of mirror elements is increased.
As a method for implementing the wobbling, an actuator is used to minutely wobble the mirror device, to shift each mirror in a diagonal direction. The shifting of each mirror in the diagonal direction fills in the gap between the mirrors, thereby improving the resolution of an image. U.S. Pat. No. 7,052,142 illustrates a method of wobbling a mirror device with an actuator connected to a mirror device to shift the reflecting direction of the light from a light source. However, application of this method of mirror element wobbling introduces many technical problems in a projection image. These problems include the projected images show a blur red “dynamic image” due to the mirror element wobbling. Furthermore, the movement of the mirror element during the time of reflecting and modulating the image projection light also adversely affects the gradation of the gray scales. These technical problems thus prevent the project system to achieve a sufficient level of resolution.
Meanwhile, the technical problems of wobbling involving the light source include the increased power consumption of the light source and the heating of the mirror device caused by the light source being continuously on. Decreasing power consumption by the light source is naturally preferable, and particularly in recent years, energy conservation has become even more important. Two factors contribute to heat build-up in a mirror device—heat resulting from external heat, such as light from the light source, and internal heat resulting from the operation of the mirror device itself.
An accumulation of heat within the mirror device causes the members constituting the mirror device to thermally expand. This causes a change in the positions of the mirrors placed on the surface of a substrate, a cracking of the substrate, a peeling off of the constituent component due to the difference in the coefficients of thermal expansion, et cetera, all of which hamper the function of a mirror device. In view of the above, it is very important to improve the radiation efficiency of a mirror device.